Fail of the week : Watt a loss

This one is a bit dated, but the lessons are still relevant. [Zach Hoeken] posted about the challenges he faced building a CNC stepper driver. He was experimenting with Toshiba motor drivers back in 2012.

The modular motor driver boards he built were based on the THB6064AH – capable of 1/64th step, and 4.5 Amps at up to 50V. [Zach] built a test jig to run the boards through their paces. A couple of messed tracks was the least of his problems – easily fixed by cutting traces and using jumper wires to correct the errors. But the header footprints for the motor drive boards got reversed. The only way out was to solder the headers on the back side.

LESSON : Always check footprint orientation and pin numbering before sending boards to fab.

The surprising part was when someone as experienced as [Zach] messed up on Ohms Law. Based on the current he wanted the motors to run at, his sense resistors needed to be 3.2W, but he’d used SMD footprints (0805 likely) instead. Those tiny resistors couldn’t be used at all, and the 5W resistors plonked on looked like an ugly hack.

Continue reading “Fail of the week : Watt a loss”

Fixing that broken laptop power jack

It seems that there’s a whole range of Toshiba Satellite laptop computers that suffer from a power jack design that is prone to breaking. We see some good and some bad in this. The jack is not mounted to the circuit board, so if it gets jammed into the body like the one above it doesn’t hose the electronics. But what has happened here is the plastic brackets inside the case responsible for keeping the jack in place have failed. You won’t be able to plug in the power adapter unless you figure out a way to fix it.

We’d wager the hardest part of this repair is getting the case open. Once inside, just cut away all of the mangled support tabs to make room for the replacement jack. The one used here has a threaded cuff that makes it a snap to mount the new part to the case. Clip off the old jack and solder the wires (mind the polarity!) and you’re in business.

Anyone know why we don’t see more of the magnetic connectors (MagSafe) that the Apple laptops have? Is it a patent issue?

[Thanks Dan]

Commercial webcam multi-touch coming soon

It looks like Toshiba has a webcam-based multi-touch display on the way. The video shows an iPod-esque photos album interface where the user stands in front of the display and manipulates it with both hands. The difference between this and some of the other multi-touch displays we’ve seen is that there is no touching necessary (goodbye fingerprints!). The user’s image is superimposed on the screen in a way that reminds us of the original Playstation Eye. Obviously this is much more refined, making us wonder if it’s the better camera, better processing, or both.

[Thanks Risingsun]